Techniques for supporting relay operation in wireless communication systems

Abstract

Techniques for supporting operation of relay stations in wireless communication systems are described. In an aspect, a bitmap may be sent by a base station and/or a relay station to identify subframes of at least two types in multiple radio frames. For example, the bitmap may indicate whether each subframe covered by the bitmap is of a first type or a second type. UEs may use the bitmap to control their operation. For example, a UE may perform channel estimation or measurement for the subframes of the first type and may skip channel estimation and measurement for the subframes of the second type. In another aspect, a base station may transmit data and/or control information on resources not used by a relay station to transmit a reference signal. This may avoid interference to the reference signal from the relay station, which may improve performance for UEs communicating with the relay station.

What is claimed is: 
     
       1. A method for wireless communication, comprising:
 generating a bitmap covering a plurality of radio frames, each radio frame comprising a plurality of subframes, wherein at least one bit in the bitmap identifies a specific type of at least two subframe types for one of the plurality of subframes, and wherein at least one bit in the bitmap indicates to receiving user equipments (UEs) whether to perform a channel characteristic inquiry using the respective subframe based on the subframe type identified by the respective bit; and 
 transmitting the bitmap to the UEs, wherein the bitmap includes at least one bit for indicating said type of at least one of said subframes of at least two types, and wherein the subframes of at least two types comprise multicast/broadcast single frequency network (MBSFN)/blank subframes and regular subframes; 
 wherein the channel characteristic inquiry includes a channel estimation based on a reference signal that is performed only for the regular subframes and is skipped for the MBSFN/blank subframes. 
 
     
     
       2. The method of  claim 1 , wherein the bitmap covers four radio frames. 
     
     
       3. The method of  claim 1 , wherein the bitmap is generated by a relay station and transmitted to the UEs. 
     
     
       4. The method of  claim 1 , wherein the bitmap is generated by a base station and transmitted to the UEs. 
     
     
       5. The method of  claim 1 , wherein the bitmap identifies different subframe types for at least two of the plurality of subframes in one of the plurality of radio frames. 
     
     
       6. The method of  claim 1 , wherein the channel characteristic inquiry includes a frequency measurement. 
     
     
       7. The method of  claim 1 , wherein the channel characteristic inquiry includes an interference estimation. 
     
     
       8. An apparatus for wireless communication, comprising:
 means for generating a bitmap covering a plurality of radio frames, each radio frame comprising a plurality of subframes, wherein at least one bit in the bitmap identifies a specific type of at least two subframe types for one of the plurality of subframes, and wherein at least one bit in the bitmap indicates to receiving user equipments (UEs) whether to perform a channel characteristic inquiry using the respective subframe based on the subframe type identified by the respective bit; and 
 means for transmitting the bitmap to the UEs, wherein the bitmap includes at least one bit for indicating said type of at least one of said subframes of at least two types, and wherein the subframes of at least two types comprise multicast/broadcast single frequency network (MBSFN)/blank subframes and regular subframes; 
 wherein the channel characteristic inquiry includes a channel estimation based on a reference signal that is performed only for the regular subframes and is skipped for the MBSFN/blank subframes. 
 
     
     
       9. The apparatus of  claim 8 , wherein the bitmap covers four radio frames. 
     
     
       10. The apparatus of  claim 8 , wherein the bitmap identifies different subframe types for at least two of the plurality of subframes in one of the plurality of radio frames. 
     
     
       11. The apparatus of  claim 8 , wherein the channel characteristic inquiry includes a frequency measurement. 
     
     
       12. The apparatus of  claim 8 , wherein the channel characteristic inquiry includes an interference estimation. 
     
     
       13. An apparatus for wireless communication, comprising:
 at least one processor, and a memory coupled to the at least one processor comprising instructions which, when executed by the at least one processor, cause the apparatus to: 
 generate a bitmap covering a plurality of radio frames, each radio frame comprising a plurality of subframes, wherein at least one bit in the bitmap identifies a specific type of at least two subframe types for one of the plurality of subframes, and wherein at least one bit in the bitmap indicates to receiving user equipments (UEs) whether to perform a channel characteristic inquiry using the respective subframe based on the subframe type identified by the respective bit; and 
 send the bitmap to the UEs, wherein the bitmap includes at least one bit for indicating said type of at least one of said subframes of at least two types, and wherein the subframes of at least two types comprise multicast/broadcast single frequency network (MBSFN)/blank subframes and regular subframes; 
 wherein the channel characteristic inquiry includes a channel estimation based on a reference signal that is performed only for the regular subframes and is skipped for the MBSFN/blank subframes. 
 
     
     
       14. The apparatus of  claim 13 , wherein the bitmap covers four radio frames. 
     
     
       15. The apparatus of  claim 13 , wherein the bitmap identifies different subframe types for at least two of the plurality of subframes in one of the plurality of radio frames. 
     
     
       16. The apparatus of  claim 13 , wherein the channel characteristic inquiry includes a frequency measurement. 
     
     
       17. The apparatus of  claim 13 , wherein the channel characteristic inquiries include an interference estimation. 
     
     
       18. A computer program product, comprising:
 a non-transitory computer-readable medium comprising: 
 code for causing at least one computer to generate a bitmap covering a plurality of radio frames, each radio frame comprising a plurality of subframes, wherein at least one bit in the bitmap identifies a specific type of at least two subframe types for one of the plurality of subframes, and wherein at least one bit in the bitmap indicates to receiving user equipments (UEs) whether to perform a channel characteristic inquiry using the respective subframe based on the subframe type identified by the respective bit; and 
 code for causing the at least one computer to send the bitmap to the UEs, wherein the bitmap includes at least one bit for indicating said one of at least one of said subframes of at least two types, and wherein the subframes of at least two types comprise multicast/broadcast single frequency network (MBSFN)/blank subframes and regular subframes; 
 wherein the channel characteristic inquiry includes a channel estimation based on a reference signal that is performed only for the regular subframes and is skipped for the MBSFN/blank subframes. 
 
     
     
       19. The computer program product of  claim 18 , wherein the bitmap identifies different subframe types for at least two of the plurality of subframes in one of the plurality of radio frames. 
     
     
       20. The apparatus of  claim 18 , wherein the channel characteristic inquiry includes a frequency measurement. 
     
     
       21. The apparatus of  claim 18 , wherein the channel characteristic inquiry includes an interference estimation.